Embodiments of the invention relate to backup power systems in a vehicle. Backup power systems may provide temporary power to operate electronic control units (ECUs) or similar control computers or processors of the vehicle upon failure of a main power supply. When the main power supply of the vehicle fails, critical functionality of the ECUs may cease unexpectedly. Backup power systems provide power for a limited time so that functionality may continue for a brief period of time. As a consequence, the ECUs may perform safe shutdowns and communicate critical vehicle messages to other vehicle systems before losing power. However, backup power systems may fail to operate when needed.